Method for manufacturing optically anisotropic film

Abstract

A method for producing an optically anisotropic film. The optically anisotropic film produced using this method has a reverse wavelength dispersion property, which can control retardation deterioration at high temperature, and can be used in polarizing plates and display devices.

1 . A method for producing an optically anisotropic film comprising:
 a step of forming an overcoat layer on one side of an optically anisotropic layer; and   a step of aging the overcoat layer at a temperature of 100° C. or higher after the step of forming the overcoat layer,   wherein the overcoat layer comprises a photoreactive compound having three or more photoreactive groups, and   wherein the anisotropic layer comprises a polymerizable liquid crystal compound satisfying Equation 1:
     R (450)/ R (550)< R (650)/ R (550),  [Equation 1]
 
   wherein, R (λ) is an in-plane retardation of a liquid crystal layer for light having a wavelength of λ nm, wherein the liquid crystal layer comprises the polymerizable liquid crystal compound oriented in a planar state.   
     
     
         2 . The method for producing an optically anisotropic film according to  claim 1 , wherein the optically anisotropic layer has an in-plane retardation value for light having a wavelength of 550 nm in a range of 100 nm to 180 nm. 
     
     
         3 . The method for producing an optically anisotropic film according to  claim 1 , wherein the three or more photoreactive groups of the photoreactive compound are selected from cinnamate groups or (meth)acryl groups. 
     
     
         4 . The method for producing an optically anisotropic film according to  claim 1 , wherein the photoreactive compound is a polymer having three or more cinnamate groups. 
     
     
         5 . The method for producing an optically anisotropic film according to  claim 1 , wherein the photoreactive compound is a monomer having three or more (meth)acryl groups. 
     
     
         6 . The method for producing an optically anisotropic film according to  claim 1 , wherein the overcoat layer has a thickness in a range of 0.1 μm to 10 μm. 
     
     
         7 . The method for producing an optically anisotropic film according to  claim 1 , wherein the overcoat layer has an in-plane retardation value for light having a wavelength of 550 nm in a range of 0 nm to 3 nm. 
     
     
         8 . The method for producing an optically anisotropic film according to  claim 1 , wherein the overcoat layer exhibits no adhesive force. 
     
     
         9 . The method for producing an optically anisotropic film according to  claim 1 , further comprising: a step of applying a liquid crystal composition on a base layer and then curing it to form the optically anisotropic layer, wherein the liquid crystal composition comprises the polymerizable liquid crystal compound. 
     
     
         10 . The method for producing an optically anisotropic film according to  claim 9 , wherein an alignment film is formed on the base layer on which the liquid crystal composition is applied. 
     
     
         11 . The method for producing an optically anisotropic film according to  claim 1 , wherein the step of forming an overcoat layer is performed by applying an overcoat composition on one side of the optically anisotropic layer, wherein the overcoat composition comprises the photoreactive compound and a solvent. 
     
     
         12 . The method for producing an optically anisotropic film according to  claim 1 , wherein the aging is performed at a temperature range of 100° C. or higher to 200° C. or lower. 
     
     
         13 . The method for producing an optically anisotropic film according to  claim 1 , wherein the aging is performed for 1 minute to 30 minutes. 
     
     
         14 . The method for producing an optically anisotropic film according to  claim 1 , wherein an absolute value of a retardation change rate (ΔR) of the optically anisotropic film is calculated by Equation 3 below:
   Δ R =( R   1   −R   2 )/ R   1 ×100%,  [Equation 3]
 
 wherein, ΔR is an in-plane retardation change rate of the optically anisotropic film after standing at high temperature, R 1  is an initial in-plane retardation value of the optically anisotropic film, and R 2  is an in-plane retardation value after leaving the optically anisotropic film at 85° C. for 500 hours, and 
 wherein the ΔR value is 5% or less.